1. Field of the Invention
This invention relates to blind anchoring devices for fastening objects to hallow walls of plasterboard, masonry, brick and the like with elongated fastener members such as screws, bolts, and the like.
2. Description of the Prior Art
It is generally known that modern day building construction techniques have been increasingly directed toward the use of wallboard panels to construct walls and partitions. Such panels may be constructed of gypsum or plaster-related materials, or of finished wood or synthetic plastics constructed to simulate material wood, for example. The wallboard materials which are often used to construct basic wall structures in place of plaster walls of the prior art are commonly referred to as dry wall, gypsum board, plasterboard, etc. Certain of these materials are marketed under trademarks such as SHEETROCK.sup..RTM. brand panels by the United States Gypsum Company of Chicago, Illinois. These wallboards are generally secured to studs which are suitably spaced according to local building codes and finished by suitable finishing techniques utilizing, for example, a tape material, plaster of paris and the like to seal the seams, and paint, wallpaper and the like for decorative purposes.
Although the relatively solid walls of the prior art were somewhat "hollow" in character, nevertheless the modern construction techniques provide walls or structures which have relatively increased "hollow" character because: (1) they are of lesser structural thickness; (2) structural intermediate materials such as wire lath and wood lath have been eliminated; and (3) they provide a relatively increased void space between the studding or other basic structure. Other well known construction materials which result in such "hollow" walls include concrete -- cast and precast -- cement, and cinder block, brick, etc.
The relatively massive construction of the earlier walls rendered them capable of supporting relatively heavy objects and substantial forces by utilizing relatively uncomplicated fasteners which relied on nails, screws and the like to complete attachment to these structures. In addition, with such earlier walls and fasteners, the higher concentration of loads resulted in greater forces-per-unit-area and did not have significant adverse affects on the walls because the substantial wall structures were capable of bearing such loads.
With the increasing use of the more hollow modern construction, it became increasingly apparent that -- without a significant design change in wall fasteners 13 the new construction would not support the objects and loads in the same manner as the earlier arrangements. For example, in a wall constructed of plasterboard sheets secured to wood studs spaced 16 inches apart, the fasteners of the prior art could only be utilized at locations corresponding to the studs. Attachments to the plasterboard portion between the studs were difficult and -- if accomplished -- almost always pierced the wallboard and were incapable of sustaining any substantial loads for any length of time.
Such disadvantages of the modern hollow walls were inconsistent with the fact that in all other respects they were either equivalent to, or better than the more costly, relatively bulky construction of the prior art. The need for blind wall fasteners which would increase the force distribution on the wall became evident, particularly where force distribution and high load-carrying capability was desirable and where attachment of the fastener to the wall could be accomplished with full access provided from one direction and limited or no access provided from the other direction. The number of such fasteners which could be utilized with such wallboards are legion. However, to date there are no fasteners which successfully eliminate the disadvantages of the prior art while offering relatively inexpensive, uncomplicated construction.
U.S. Pat. No. 3,211,042 to Fischer relates to a pivotal anchoring assembly for screws and the like in which a single extension has connected at one end a fastener retaining means and, at the opposite end, a knob. The construction does not facilitate positive or even substantial blind control of the fastener components when they are inserted into a wall opening, as is generally required in modern day construction, particularly at mass production construction sites. Further, the device of Fischer does not provide the positive attachment which is also desirable and -- in many cases -- necessary in modern day construction.
U.S. Pat. No. 2,998,743 to Apfelzweig relates to a toggle bolt having a channel member which defines generally oppositely positioned U-shaped slots for reception of resilient sheet metal arms therein. The sheet metal arms are connected to one end to a washer which acts as a terminal head of the toggle bolt. When the channel member is inserted into a wall opening and positioned behind the concealed wall surface, fastening is accomplished in a well known manner by inserting a threaded member through the washer head and threadedly engaging a mating threaded opening of the channel member. This begins the movement of the channel member as it advances toward the blind surface of the wall along the length of the threaded fastener as it is rotated. The metal construction and the relatively rigid complex structure of this toggle bolt render it relatively difficult to produce and substantially more complicated to operate than would otherwise be desirable.
U.S. Pat. No. 2,398,220 to Gekpcke relates to a toggle lock which utilizes a pair of wings on the blind side of the wall to maintain the fastening effect. However, the wall fastening is primarily dependent upon the fastener bolt or screw remaining in position, and the basic wall attachment is not capable of being fastened to the wall as positively and securely as may be desirable. Further, the indirect control over the locking wings positioned behind the wall, from a position forward of the wall, is relatively negligible once direct control is relinquished.
U.S. Pat. No. 3,175,452 to Leitner relates to a fastening means adapted for connecting members whose rear sides are inaccessible. The structure of the Leitner device is directed toward a unitary blind bolt construction in which is provided a resilient extension for the purpose of positioning a threaded nut behind the concealed surface of the wall.
U.S. Pat. No. 3,552,258 to Warner relates to bolt anchors for attainment within a borehole of a rock or the like. Although the anchor contemplates a blind fastening attachment, the structure disclosed is neither adaptable nor useful to promote the type of blind fastening capability and control as is provided in the present invention.
A particularly useful development is disclosed in U.S. Pat. No. 3,651,734 to McSherry which relates to an expansible fastener engageable with one end of an opening and having an expandable overcenter toggle lock on the other side of the opening to maintain the fastener in stable overcenter position within a hollow wall opening. While this development has proven to be extremely useful and successful, a particularly dimensioned construction is adaptable for attachment with wallboards of a relatively limited range of thicknesses.
U.S. Pat. No. 1,521,026 to Hubener relates to an anchor bolt adapted for blind fastening by utilizing resilient means such as rubber bands to retain the tension on a resilient pull member.
This, it can be observed that while numerous constructions of the prior art fasteners have often relied upon the bolt, screw or other fasteners to retain their position within the wall, none of these fasteners is capable of being securely positioned on the wall generally independently of the elongated fastener. In addition, modern construction techniques have dictated new requirements necessitating greater blind control and more positive and quick fastening capability and installation than is possible with the earlier anchor bolts. We have invented a fastener which avoids the disadvantages of the prior art and is particularly useful with walls of numerous thicknesses wherein full access is generally provided from one direction. Our fastener has proven to be particularly successful for permanent and reusable attachment to modern wall constructions wherein ready access to one side is fully provided, and limited or no access is provided from a second side. The present construction is universally adaptable for use with walls of numerous types, including walls constructed of panels, cement, concrete, brick and the like. Further, a single fastener has particular utility with walls of numerous thicknesses and provides a permanent, reusable fastener with such walls.